It is estimated that at least 50% of the population has some form of allergy. Approximately 20 million patients are currently tested for allergies using a number of techniques, for example, skin prick test, intradermal test, blood test, and skin patch test. Allergy test methods, such as the skin prick test are invasive and manual, involving depositing drops of many allergens on a subject's back, forearm, or other smooth body surface, labeling the region for identification, and then pricking the region with a needle to allow penetration of the allergy into the subject's body. The intradermal test is even more invasive, involving injecting a small amount of various allergens into the subject's skin. Due to the nature of these processes, large areas of the subject's skin tend to be affected.
Subjects undergoing these pin prick and intradermal tests then wait a prescribed period of time to allow the allergens a chance to react with their skin. Test regions must be large enough to easily be identified and evaluated by the human eye or by photographs which are then printed or enlarged. Although these forms of allergy testing often cover a large area of a patient's body, these manual determinations of allergic reaction provide the medical practitioner with a snapshot in time which has been shown to be useful in screening patients for allergic reactions.
Blood testing provides a highly invasive, yet possibly more convenient method of allergy testing. Unfortunately, blood testing does not surpass the sensitivity, specificity, and predictive value of the skin test. Blood test results are often dependent upon the laboratory which is performing the test. Blood testing for allergies is also a more expensive option.
Therefore, there is a need for a minimally invasive allergy testing system which does not need to cover large areas of a patient's skin, which can be automated to a large extent, which can be correlated to existing skin testing data, which offers more than a snapshot in time of an allergic reaction, which is economical, and which is easy to use and manufacture.